pushrods making me mad!

[Chevysucks]

I just ordered new pushrods for my stang because my old ones were bent and had a crack on one of them. I ordered comp cams extra hardend pushrods for 5.0 hydolic roller. Stock length- 6.272 i think thats stock length. well i got them yesterday and i put them in and bolted down the crane cams energizer 1.7 roller rockers and after i torqued them i could grab a push rod and move it up and down a little bit till it touched the back of the rocker where its supposed to be seated. my dad was trying to help me out and he told me i had no preload. He told me to send the pushrods that i just got back and order the crane cams hardended pushrods that are .117 longer- 6.375 i think they are. I was just wondering what it is that i have to order longer ones.
my engine is 302 50ho bored to 306. gt heads that have been port and polished and x303 camshaft, stock intake.
if anyone had any ideas please tell me thanks.